Did they give me Bantam cohcin's by mystake?

We ordered 4 st. run Cochin's Suppose to be full size, with our ornamental layer collection from MM, they arrived healthy and happy on June 2. They sent 3 blue and 2 silver laced so we got an extra blue! Yeah.
However as I have watched them grow I have noticed that two of the blue are large and have all there feathers while the other blue and the 2 silver laced are tiny they are smaller then our White Faced Spanish and other Ornamental chicks. And they are taking alot longer to get there feathers.
Is it possible these are banties instead of full size cochins??
or do some just take longer then others to grow.
Melissa

Different strains of birds can also have large growth rate and terminal size differences so I wouldn't worry. I've had different runs of silkies end up 6-8 ounces different at adult weight. And for a 32 ounce bird or so, that can be significant.

I have Cochins in bantam and standard. The chicks are all looking different at 7 weeks old. The bantams were bred and hatched here but I bought the standards at a day old.
The bantams are now finally feathered out as the standards did feather out sooner but could have been genetics in the works.
They run and play together and I can easily pick out the bantams but the standards are different sizes, especially the roos and pullets.

Thanks that makes me feel better I never even thought to look and see if they sold SL in bantams or not. It's just so weird seeing the two huge ones next to the three little ones. I should get a pic just so you can all see.
Do you think it could have something to do with Hens and Roosters??? I hope not cause that would mean both my Silver laced ones are Roosters.

While we are on the subject how about Brahma's? we have what I think is a Dark Brahma but then I wonder could it be a bantam? maybe it is my free rare chick? the Light brahmas are like twice the size of it.